published_or_final_version / Pharmacology / Doctoral / Doctor of Philosophy

Rats given L-Ascorbic Acid in their drinking water prior to and during starvation did not develop severe ulceration in the glandular portion of their stomachs. Control rats which were either nontreated or given deactivated L-Ascorbic Acid developed severe stomach pathology on the starvation regimen. The present study was based on the finding that food deprivation results in severe rumenal ulceration in rats. Given that L-AA is essential in maintaining tissue integrity and that ulcers are examples of tissue degeneration, the L-AA in large amounts could retard, or prevent, the formation of starvation induced stomach ulcers in rats. The results show that large amounts of active L-AA were beneficial in maintaining the integrity of rat gastrointestinal tissue exposed to starvation conditions which, in the vitaimin's absence, induces deterioration.

The pattern of mucosal blood flow in normal human stomachs, and benign gastric ulcers was assesed with laser Doppler flowmetry and the relationship between a single determination of ulcer blood flow and the systemic level of growth factors was investigated. A significant ascending gradient in mucosal blood flow from the antrum to fundus was demonstrated. Different levels of cellular activity in the regions of the stomach may explain this gradient. In the gastric ulcers that healed on standard medical therapy mucosal blood flow was significantly increased in comparison to normal stomachs. In the ulcers that were refractory to standard medical therapy mucosal blood flow was significantly lower than in normal stomachs and healing ulcers. Higher systemic levels of the growth factor bFGF were demonstrated in healing ulcers compared to non-healing ulcers. Gastric mucosal blood flow can increase in response to the increased metabolic demands of healing, however impairment of this response may be an important factor preventing healing of benign gastric ulcers. It would appear that non-healing of gastric ulcers can be predicted at initial diagnosis by reduced peri-ulcer gastric mucosal blood flow and low blood levels of bFGF. / Thesis (M.Med.Sc.)-University of Natal, Durban, 1999.